Monoclonal antibodies (mAb) are valuable therapeutics for treating cancer and other diseases, but their high cost makes them attractive targets for counterfeiting or illegal distribution. Numerous cases have occurred both in the US and worldwide and the complexity of the pharmaceutical distribution network makes the problem likely to persist. The goal of this project is to develop a simple and inexpensive lateral flow immunoassay that can be used to quickly determine the integrity of a monoclonal antibody therapeutic. Using mimetope peptides that mimic the native antigen epitope recognized by a give mAb, our test will discriminate between active mAb and other protein or immunoglobulin contaminants. Mimetope peptides have been developed for the top three mAb used in oncology: bevacizumab, trastuzumab, and rituximab. The rituximab mimetopes have already been developed in an ELISA format and used for pharmacokinetic studies, the remaining two will be similarly validated in Aim 1 of this proposal. In Aim 2, we will translate the ELISA assay to the lateral flow immunoassay format. In Aim 3 we will collaborate with a top clinician-scientist at the Moores UCSD Cancer Center to conduct a double blind study of the prototype tests for each of the mAb, determining their accuracy as well as their ability to detect either saline or polyclonal human immunoglobulin. Successful development of these products will enable oncologists and their patients to have added confidence that these potentially life-saving therapies are genuine and active at the time of administration.